Italian squadrons of aeroplanes bombarded the railway station at Mattarello, in the Lagarina Valley, and encampments at the junction of the Nos and Campomulo Valleys on the Asiago Plateau, while Austrian aeroplanes dropped bombs on Padova, Giorgio di Nogaro, and Porto Rosega.
The Italian advance was steadily maintained from now on, not without, however, finding everywhere the stiffest kind of resistance, which at times made it even possible for the Austro-Hungarians to gain slight local successes. These, however, were not extensive or frequent enough to change the general picture of military operations on the Austro-Italian front. The Austrians, though still on Italian territory in a number of localities, were on the defensive with the Italians, though making only very slow and painful progress, unquestionably on the offensive.
On June 16, 1916, the Italians advanced northeast of Asiago, between the Frenzela Valley and Marcesina. Notwithstanding the difficult and intricate nature of the terrain and the stubborn resistance of the Austrians, intrenched and supported by numerous batteries, the Italian troops made progress at the head of the Frenzela Valley, on the heights of Monte Fior and Monte Castel Gomberto and west of Marcesina. The best results were attained on the right wing, where Alpine troops carried the positions of Malga Fossetta and Monte Magari, inflicting heavy losses on the Austrians and taking 203 prisoners, a battery of 6 guns, 4 machine guns, and much material.
During the next few days the most fierce fighting occurred on the plateau of Sette Comuni. All Austrian attempts to resume the offensive and continue their advance failed. The Italian advance was scarcely more successful; fighting had to be done in the most difficult territory; strong Austrian resistance developed everywhere. Thunderstorms frequently added to the difficulties already existent. Yet slowly the Italian forces pushed back the invader.
On June 18, 1916, Alpine troops carried with the bayonet Cima di Sidoro, north of the Frenzela Valley. Fighting developed in the Boite sector, where the Italians had made some slight gains during the previous days, which the Austrians tried to dispute. Heavy Italian artillery bombarded the railway station at Toblach and the Landro road in the Rienz Valley. Artillery and aeroplane activity was extremely lively during this period. Not a day passed without artillery duels at many scattered points along the entire front from the Swiss border down to the Adriatic. Aeroplane squadrons of considerable force paid continuously visits to the opposing lines, dropping bombs on lines of communication and railway stations.
Alpine troops captured a strong position for the Italians on June 20, 1916, at the head of the Posina Valley, southwest of Monte Purche. On the 22d the Italians pushed their advance beyond Romini in the Arsa Valley, east of the Mezzana Peak, and on the Lora Spur, west of Monte Pasubio.
On the same day the Austrians counterattacked with extreme violence at Malga Fossetta and Castel Gomberto, but were repulsed with heavy losses. On the 21st a further Austrian attack at Cucco di Mandrielle resulted in a rout. On the 22d the Italians, while holding all the Austrian first-line approaches under heavy fire to prevent the bringing up of reserves, attacked on the entire front, but still encountered a strong resistance. During the night of the 24th the remaining peak of Malga Fossetta, held by the Austrians, Fontana Mosciar, and the extremely important Mandrielle were taken by storm, while the Alpini on the right made themselves masters of the Cima Zucadini by the 22d.
Henceforth retreat was inevitable, and during the night of the 25th the Italians on Monte Fior, seeing that the Austrian resistance had greatly diminished, pushed their offensive vigorously. Shortly after the advance was begun along the whole right. Monte Cengio, which had received an infernal bombardment for three days and nights, fell at last, and the advance proceeded apace.
On June 26, 1916, Italian troops in the Arsa Valley carried strong trenches at Mattassone and Naghebeni, completing the occupation of Monte Lemerle. Along the Posina front, after driving out the last Austrian detachments from the southern slopes of the mountain, the Italians crossed the torrent and occupied Posina and Arsiero, advancing toward the northern slopes of the valley.
On the Sette Comuni Plateau Italian infantry, preceded by cavalry patrols, reached a line running through Punta Corbin, Fresche, Concafondi, Cesuna, southwest of Asiago, and passing northeast of the Nosi Valley, and occupied Monte Fiara, Monte Lavarle, Spitzkaserle and Cimasaette.